Wings Over the Watcher

In separate locations in Staffordshire, three separate tableaux are being played out. DI Joanna Piercy is writing to her lover to try and explain recent events; her sidekick Mike Korpanski is filling in insurance forms after his wife has had a prang in the car; and an unknown person is penning love letters to a local doctor.
It seems that no one could lead a more mundane life than Beatrice Pennington. Unexciting; mid-forties; married; a part-time librarian; grown-up kids; her life appears unremarkable. But then drama unfolds around her...